A glossary of acronyms and abbreviations associated with emergency services calls is contained in NENA Master Glossary of 9-1-1 Terminology, NENA 00-001, Version 16, dated Aug. 22, 2011 and is incorporated herein by reference in its entirety.
PSAP call takers dispatch emergency assistance such as police, fire, and medical personnel in response to phone calls made to an emergency telephone number which, in the case of the United States, is 9-1-1. For 9-1-1 calls from a traditional wireline phone, the dispatch address is pre-configured and stored in an ALI database. For 9-1-1 calls from a mobile phone, there is no fixed address associated with the mobile phone. To enable PSAP call takers to dispatch emergency assistance to the mobile phone caller, wireless carriers have implemented a variety of location-determining technologies to provide the caller's latitude and longitude (hereafter referred to as “X,Y”).
Having accurate caller X,Y is critical for ensuring that first responders arrive at the correct location. The FCC recognized the importance of accurate X,Y in 1996 by adopting rules that required wireless carriers to implement E911 location-determining services. The FCC divided its wireless E911 rules into two stages. The initial stage was called Phase I and required wireless carriers to deliver by April 1998 E911 service that included the caller's telephone number and the location of the cell site or base station that handled the call. The second phase was called Phase II and required delivery, under a phased-in schedule, now extending until January 2019, E911 service that includes X,Y of the mobile phone caller within specific accuracy and reliability parameters, depending on the location technology, as follows:                (a) Using network-based technologies: within 100 meters for 67 percent of calls, and 300 meters for 90 percent of calls;        (b) Using handset-based technologies: within 50 meters for 67 percent of calls, and 150 meters for 90 percent of calls.        
Despite the FCC rules requiring improvements in location accuracy, there are multiple reasons why an X,Y provided to the PSAP does not result in a useful address for dispatching emergency assistance (hereafter referred to as a “dispatch address”). For some mobile phone calls, only Phase I X,Y is made available to the PSAP. Since Phase I location only identifies the caller's cell site and can have a range as large as 22 miles for GSM technology, the Phase I X,Y provided to the PSAP is not sufficient to determine a dispatch address. For mobile phone calls that are routed to a PSAP with Phase II location, the accuracy of that location is often outside the 100 meter range (or 50 meters for carriers using handset-based technologies). This is a common problem for mobile phones that rely on a handset-based technology such as GPS, since indoor GPS coverage is typically poor due to 1.5 GHz RF propagation properties. An additional cause for dispatch address errors occurs when an X,Y is converted at the PSAP into a dispatch address by using mapping or GIS tools to identify the closest street address to the X,Y. Depending on the precision and accuracy of the X,Y, the area described by the X,Y may cover many street addresses and the center of the area described by the X,Y and its precision may not be the nearest street address to the actual emergency.
The problem of identifying a dispatch address is further exacerbated when an emergency occurs at a building with many rooms or multiple floors, each with many rooms. In these situations, a street address, even if correct, is inadequate. The net result is that first responders arriving at the location to which they are dispatched often face the difficult task of searching for and locating the party who called 9-1-1 before assistance can be rendered.
Prior to this invention, a common approach used by first responders for locating the person who called 9-1-1 was to call the 9-1-1 caller's phone number to get further verbal instructions. However, there are cases when this approach will not work. The party who called 9-1-1 for assistance might have had a medical emergency preventing him or her from answering a follow-up phone call. Or the party who called 9-1-1 might be hiding silently from an intruder or be occupied fighting a fire. Even if the PSAP provided a precise building, floor and room number where the 9-1-1 caller should be located, it is possible that the 9-1-1 caller may have moved to another floor or room in the building to escape an encroaching file or to hide from an intruder. In situations like these, first responders may waste precious time searching for the 9-1-1 caller.
In addition to locating the party requiring assistance, first responders arriving to a dispatch address face a new challenge, known in the industry as 9-1-1 “SWATing”. This dangerous practice results in a PSAP call taker being tricked into dispatching an armed SWAT response to an innocent address. To address this new challenge, when armed first responders arrive on scene, they need to ensure they are at the correct location.
There is a need for a system and method to help first responders efficiently search for and locate a 9-1-1 caller.